DSG Overview - intelvwi/DSG GitHub Wiki
Immersive virtual environments (also called virtual worlds) such as those running on the OpenSimulator (http://opensimulator.org/wiki/Main_Page) platform require the simultaneous simulation of many diverse types of behaviors. For example, an OpenSimulator region simulator manages client connections, executes scripted object behaviors and simulates physics such as gravity and collisions. The traditional software architecture of such a platform tightly integrates all these simulations/operations in the same simulator process. Hence, in such a platform, operations inside a virtual space, e.g. an OpenSim region, is constrained by the computation and communication capacity of the server that hosts the region’s simulator process. As a result, each region can only support a limited number of concurrent users or a limited level of scene complexity (e.g. limited number of objects or limited complexity of object behaviors).
Distributed Scene Graphs (DSG) is a technology designed to address the above scalability challenge in existing virtual world platforms. (The term Scene Graph here refers to the data structure that stores the state of a virtual space, also called a scene.) It scales operations in a virtual space by efficiently leveraging additional hardware resources. That is, when the workload inside a virtual space exceeds the capability of a single server, DSG enables distributing the workload across several servers while maintaining the performance and user experience. For instance, for the workload running in an OpenSim region, DSG enables the operations to run on several servers: physics simulation runs on one server, scripts on a second server, and a set of additional servers handles client connections. The DSG update propagation services (a type of synchronization service) glues the results from all the servers and presents a consistent view of the virtual world to users. As an example, it was publically demonstrated that with DSG, up to 1,000 users were able to interact with each other concurrently, where the workload was spread across multiple servers. http://software.intel.com/en-us/videos/work-or-play-online-with-a-cast-of-thousands
More information of DSG work can be found at http://www.intel.com/content/www/us/en/research/intel-labs-scalable-virtual-worlds.html.